Fluid control valves are used in a wide variety of applications to control the flow and/or pressure of a fluid. The fluid may comprise a liquid, a gas, or a combination thereof. The fluid may include suspended particulates. While fluid control valves vary widely in the specific configuration used to open and close a fluid communication path through the valve, one specific type of fluid control valve is a poppet valve. Poppet valves generally include one or more valve orifices and a poppet member that moves to contact and seal the valve orifice(s) in order to perform a valve function. Poppet valves can be actuated in a variety of different manners. For example, some poppet valves are actuated using a solenoid. Alternatively, the poppet valve can be actuated by a pilot fluid source. In solenoid-actuated poppet valves, the solenoid comprises an electric current that passes through a coil, with the coil typically formed around a magnetic core. The energized solenoid generates a magnetic field. The magnetic field operates on a movable armature connected to the poppet member. Typically, the poppet valve also includes a spring or other biasing member that generates a biasing force in opposition to the magnetic field. Therefore, in the absence of a magnetic field generated by the solenoid, the poppet member is moved into a normally open or a normally closed position.
Poppet valves have several advantages. Poppet valves can accommodate high flow rates. Poppet valves can accommodate varying flow rates. Poppet valves can form a highly reliable seal, even in the presence of moisture, dirt, debris, etc. Due to the benefits that poppet valves provide, they are very popular for industrial applications.
FIG. 1 shows a prior art solenoid actuated poppet valve 100. The poppet valve 100 includes a housing 101, a fluid inlet 102, a fluid outlet 103, a fluid chamber 104, a valve seat 107, and a poppet member 106. The poppet member 106 is adapted to form a substantially fluid-tight seal with the valve seat 107. The poppet member 106 is coupled to a movable armature 111. The movable armature 111 moves in response to a magnetic field produced by an electromagnetic coil 108 and a magnetic core 110. The electromagnetic coil 108 is wrapped around a bobbin 109. When an electrical current is provided to the coil 108, a magnetic flux is created. The magnetic core 110 is provided to redirect the magnetic flux through the movable armature 111, thereby pulling the movable armature 111 and thus, the poppet member 106 towards the magnetic core 110. A biasing member 112 may also be provided that biases the poppet member 106 in a direction opposite the magnetic force. In the absence of the magnetic flux, the biasing member 112 can move the poppet member 106 in a direction opposite the magnetic force. The general operation of solenoid-actuated poppet valves is known in the art and therefore, a more detailed discussion is omitted for brevity of the description.
Often times, the fluid at the inlet 102 of the valve 100 acts on the poppet member 106 and provides a biasing force on the poppet member 106. This biasing force increases as the pressure at the inlet 102 increases. In order to keep the poppet member 106 against the valve seat 107, the biasing member 112 must be stronger than the force of the fluid pressure, which acts across an area defined by π*r2 as is generally known in the art. Therefore, assuming a circular cross-section, the biasing force acting on the poppet member 106 by the fluid pressure is determined as:Fb=P*π*r2  (1)
Where:
Fb is the biasing force;
P is the fluid pressure; and
r is the radius of the poppet member.
As the fluid pressure increases, the strength of the biasing member 112 increases and a stronger electromagnetic force from the electromagnetic coil 108 is required. The biasing force from the fluid can be minimized by making the valve smaller; however, this also results in a restricted flow through the valve when the valve is opened. Conversely, in order to obtain a higher flow rate, the valve is often enlarged. However, this approach results in an increased biasing force from the fluid pressure and thus, requires a stronger valve actuating force to overcome the fluid pressure and actuate the valve. The stronger valve actuating force often results in increased power consumption required by the electromagnetic coil 108. Consequently, there is typically a tradeoff between allowable flow rate and the power consumption of the valve.
Although power consumption may not be critical in certain valve applications, such as the prior art solenoid actuated poppet valve 100, for battery powered valves, power consumption is typically a major concern. Therefore, battery powered valves often are relatively small and restrict the flow through the valve. The restriction is not always ideal and there are some situations where higher flow rates and/or faster actuation times may be desired.
Therefore, there is a need in the art for a motorized valve that can operate with increased fluid pressure and/or flow rate. The embodiments described below overcome this and other problems and an advance in the art is achieved. The embodiments described below provide a motorized sleeve valve. The motorized sleeve valve advantageously actuates a sleeve surrounding at least a portion of a valve body. Therefore, the pressure drop through the opened valve is minimal and therefore, the flow restriction is reduced. Consequently, the fluid pressure provides minimal force on the sleeve and thus, a much smaller motor can be used to actuate the valve without sacrificing the valve's flow rate capabilities.